Officers who police Scotland's railways are to be armed with Tasers in a bid to increase security on the network.

The British Transport Police said the move was a "proportionate response" in the face of a mounting terrorism threat.

Specially trained officers will begin carrying the stun weapons over the next few weeks.

It brings the Scottish force into line with their counterpart in England, where Tasers have been used since 2011.

The weapons are used to incapacitate suspects through the use of an electric current.

Temporary Assistant Chief Constable Alun Thomas said: "This decision is not based on specific intelligence of any criminal behaviour or imminent threat, but will allow us the option to deploy Taser devices where, in the course of their duty, an officer needs to protect the public or themselves by using force.

"The current threat to the UK from international terrorism remains 'severe', meaning an attack is highly likely.

"Recent terrorist attacks across the world are a stark reminder that the threat from terrorism is a genuine risk, and it is important that we keep our security measures and operational tactics under constant review."

In one instance, police used a weapon against a man armed with a large knife - a move which "undoubtedly" prevented people from being hurt, according to Mr Thomas.

He said: "In our assessment, the introduction of Taser devices in Scotland is a proportionate response and provides an additional option for our officers to consider when confronted with a genuine threat to themselves or the public.

"By way of example, in December last year, police deployed a Taser device against a man armed with a large bladed knife, preventing him cutting the throat of stranger who he had targeted at random at Leytonstone station, east London.

"Undoubtedly the use of the Taser device in this incident prevented even further harm to the travelling public."

"We believe that the public in Scotland deserve the same level of protection as people elsewhere on the rail network."

Serious incidents

British Transport Police said they reached the decision on Tasers following "detailed discussions" with Police Scotland.

Scottish Ministers have also been briefed.

The force refused to reveal how many officers would receive the training required to carry Tasers "for security reasons".

Ch Supt John McBride, divisional commander for the Scotland, said Taser use by officers would be monitored.

"Every time we unholster it, it will be subject to review," he told the BBC's Good Morning Scotland programme.

"It will be subject to internal review by our own specialists, but also we have agreed with the Police Investigations and Review Commissioner that where there is a discharge and serious incidents involving Taser then we will refer ourselves to the Pirc for them to review the circumstances of the case and if necessary carry out an investigation."